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Okamura E, Ikeda K, Mano-Usui F, Kawashima S, Kondo A, Inagaki N. Augmentation of Growth Hormone by Chewing in Females. Nutrients 2023; 15:3628. [PMID: 37630818 PMCID: PMC10458618 DOI: 10.3390/nu15163628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/11/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Sarcopenia is an age-related condition characterized by progressive loss of muscle mass and strength. Age-related decline in the secretion of growth hormone (GH), a condition called somatopause, is thought to play a role in sarcopenia. As pharmacological GH has adverse effects, we attempted to increase physiological GH. While the relationship between chewing and ghrelin levels has been studied, there are no reports on the relationship between chewing and GH. The aim of this study was to clarify the effects of chewing on the muscle anabolic hormones serum GH and plasma ghrelin. Thirteen healthy adults ingested a chewy nutrition bar containing 5.56 g of protein, 12.71 g of carbohydrate, and 0.09 g of fat on two different days, chewing before swallowing in one trial and swallowing without chewing in the other. Blood samples were taken before and after ingestion (0, 15, 30, and 60 min); GH, acylated ghrelin, glucose, insulin, amino acids, and lactate were measured. Two-way repeated ANOVA revealed a significant difference in the GH concentrations between the "Chew trial" and "Swallow trial" in females (p = 0.0054). However, post-hoc analyses found no statistically significant difference at each time point. The area under the curve of the percentage increase in GH was significantly increased in the "Chew trial" compared with the "Swallow trial" in females (12,203 ± 15,402% min vs. 3735 ± 988% min, p = 0.0488). Chewing had no effect on glucose, insulin, amino acids, or lactate concentrations. Thus, we found that chewing a protein supplement rather than swallowing it without chewing elevates the blood GH concentration. These results serve as a rationale for larger research and longitudinal studies to confirm the impacts of chewing on GH secretion.
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Affiliation(s)
- Emi Okamura
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
| | - Kaori Ikeda
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
- Department of Clinical Research Facilitation, Institute for Advancement of Clinical and Translational Science, Kyoto University Hospital, Kyoto 606-8507, Japan
| | - Fumika Mano-Usui
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
| | - Sachiko Kawashima
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
- Preemptive Medicine and Lifestyle Related Disease Research Center, Kyoto University Hospital, Kyoto 606-8507, Japan
| | - Aki Kondo
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; (E.O.)
- Medical Research Institute KITANO HOSPITAL, P.I.I.F. Tazuke-Kofukai, Osaka 530-8480, Japan
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2
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Flux coupling, not specificity, shapes the transport and phylogeny of SLC6 glycine transporters. Proc Natl Acad Sci U S A 2022; 119:e2205874119. [PMID: 36191186 PMCID: PMC9564218 DOI: 10.1073/pnas.2205874119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ATB[Formula: see text] (SLC6A14) is a member of the amino acid transporter branch of the SLC6 family along with GlyT1 (SLC6A9) and GlyT2 (SLC6A5), two glycine-specific transporters coupled to 2:1 and 3:1 Na[Formula: see text]:Cl[Formula: see text], respectively. In contrast, ATB[Formula: see text] exhibits broad substrate specificity for all neutral and cationic amino acids, and its ionic coupling remains unsettled. Using the reversal potential slope method, we demonstrate a 3:1:1 Na[Formula: see text]:Cl[Formula: see text]:Gly stoichiometry for ATB[Formula: see text] that is consistent with its 2.1 e/Gly charge coupling. Like GlyT2, ATB[Formula: see text] behaves as a unidirectional transporter with virtually no glycine efflux at negative potentials after uptake, except by heteroexchange as remarkably shown by leucine activation of NMDARs in Xenopus oocytes coexpressing both membrane proteins. Analysis and computational modeling of the charge movement of ATB[Formula: see text] reveal a higher affinity for sodium in the absence of substrate than GlyT2 and a gating mechanism that locks Na[Formula: see text] into the apo-transporter at depolarized potentials. A 3:1 Na[Formula: see text]:Cl[Formula: see text] stoichiometry justifies the concentrative transport properties of ATB[Formula: see text] and explains its trophic role in tumor growth, while rationalizing its phylogenetic proximity to GlyT2 despite their extreme divergence in specificity.
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3
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Exercise training reverses the negative effects of chronic L-arginine supplementation on insulin sensitivity. Life Sci 2017; 191:17-23. [DOI: 10.1016/j.lfs.2017.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/24/2017] [Accepted: 10/01/2017] [Indexed: 12/14/2022]
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4
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Pagani S, DE Filippo G, Genoni G, Rendina D, Meazza C, Bozzola E, Bona G, Bozzola M. Growth hormone receptor polymorphisms and growth hormone response to stimulation test: a pilot study. Minerva Pediatr (Torino) 2016; 73:379-382. [PMID: 27355158 DOI: 10.23736/s2724-5276.16.04576-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND No gold standard pharmacological stimulation test exists for the diagnosis of growth hormone deficiency (GHD). In addition, the genetic factors that influence growth hormone (GH) responses remain unclear. This study aimed to determine whether polymorphisms in exon 6 of the GH receptor gene influence responses to the L-arginine GH stimulation test. METHODS This study included 27 prepubertal patients with confirmed GHD. GHD was defined as a peak GH level <8 ng/mL in response to pharmacological stimulation. The mean GH peak after L-arginine stimulation was 2.9±2.9 ng/mL. RESULTS The included patients had the following genotypes at the third position of codon 168: AA (N.=1), AG (N.=15) and GG (N.=11). Patients carrying the AA and AG genotypes exhibited stronger responses to arginine than patients with the GG genotype (3.1±2.7 vs. 1.5±1.3 ng/mL, P=0.01). CONCLUSIONS The approach employed in this study could elucidate GH profiles under physiological and pathological conditions, facilitating improved interpretation of pharmacological stimulation tests.
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Affiliation(s)
- Sara Pagani
- Unit of Pediatric and Adolescentology, Department of Internal Medicine and Therapeutics, Foundation IRCCS Polyclinic San Matteo, University of Pavia, Pavia, Italy
| | | | - Giulia Genoni
- Department of Health's Sciences, University of Eastern Piedmont, Novara, Italy
| | - Domenico Rendina
- Department of Clinical Medicine and Surgery, Federico II University, Naples, Italy
| | - Cristina Meazza
- Unit of Pediatric and Adolescentology, Department of Internal Medicine and Therapeutics, Foundation IRCCS Polyclinic San Matteo, University of Pavia, Pavia, Italy
| | - Elena Bozzola
- Department of Pediatrics, Bambino Gesù Children Hospital, Rome, Italy
| | - Gianni Bona
- Department of Health's Sciences, University of Eastern Piedmont, Novara, Italy
| | - Mauro Bozzola
- Unit of Pediatric and Adolescentology, Department of Internal Medicine and Therapeutics, Foundation IRCCS Polyclinic San Matteo, University of Pavia, Pavia, Italy -
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5
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Díaz-Soto G, Rocher A, García-Rodríguez C, Núñez L, Villalobos C. The Calcium-Sensing Receptor in Health and Disease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 327:321-369. [PMID: 27692178 DOI: 10.1016/bs.ircmb.2016.05.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The extracellular calcium-sensing receptor (CaSR) is a unique G protein-coupled receptor (GPCR) activated by extracellular Ca2+ and by other physiological cations including Mg2+, amino acids, and polyamines. CaSR is the most important master controller of the extracellular Ca2+ homeostatic system being expressed at high levels in the parathyroid gland, kidney, gut and bone, where it regulates parathyroid hormone (PTH) secretion, vitamin D synthesis, and Ca2+ absorption and resorption, respectively. Gain and loss of function mutations in the CaSR are responsible for severe disturbances in extracellular Ca2+ metabolism. CaSR agonists (calcimimetics) and antagonists (calcilytics) are in use or under intense research for treatment of hyperparathyroidism secondary to kidney failure and hypocalcemia with hypercalciuria, respectively. Expression of the CaSR extends to other tissues and systems beyond the extracellular Ca2+ homeostatic system including the cardiovascular system, the airways, and the nervous system where it may play physiological functions yet to be fully understood. As a consequence, CaSR has been recently involved in different pathologies including uncontrolled blood pressure, vascular calcification, asthma, and Alzheimer's disease. Finally, the CaSR has been shown to play a critical role in cancer either contributing to bone metastasis and/or acting as a tumor suppressor in some forms of cancer (parathyroid cancer, colon cancer, and neuroblastoma) and as oncogene in others (breast and prostate cancers). Here we review the role of CaSR in health and disease in calciotropic tissues and others beyond the extracellular calcium homeostatic system.
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Affiliation(s)
- G Díaz-Soto
- Endocrinology and Nutrition, Valladolid University Hospital, Valladolid, Spain
| | - A Rocher
- Department of Biochemistry and Molecular Biology and Physiology, University of Valladolid, Valladolid, Spain; Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - C García-Rodríguez
- Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - L Núñez
- Department of Biochemistry and Molecular Biology and Physiology, University of Valladolid, Valladolid, Spain; Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain
| | - C Villalobos
- Institute of Molecular Biology and Genetics (IBGM), University of Valladolid and National Research Council (CSIC), Valladolid, Spain.
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Alamshah A, McGavigan AK, Spreckley E, Kinsey-Jones JS, Amin A, Tough IR, O'Hara HC, Moolla A, Banks K, France R, Hyberg G, Norton M, Cheong W, Lehmann A, Bloom SR, Cox HM, Murphy KG. L-arginine promotes gut hormone release and reduces food intake in rodents. Diabetes Obes Metab 2016; 18:508-18. [PMID: 26863991 PMCID: PMC4982043 DOI: 10.1111/dom.12644] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/31/2016] [Accepted: 02/07/2016] [Indexed: 12/14/2022]
Abstract
AIMS To investigate the anorectic effect of L-arginine (L-Arg) in rodents. METHODS We investigated the effects of L-Arg on food intake, and the role of the anorectic gut hormones glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), the G-protein-coupled receptor family C group 6 member A (GPRC6A) and the vagus nerve in mediating these effects in rodents. RESULTS Oral gavage of L-Arg reduced food intake in rodents, and chronically reduced cumulative food intake in diet-induced obese mice. Lack of the GPRC6A in mice and subdiaphragmatic vagal deafferentation in rats did not influence these anorectic effects. L-Arg stimulated GLP-1 and PYY release in vitro and in vivo. Pharmacological blockade of GLP-1 and PYY receptors did not influence the anorectic effect of L-Arg. L-Arg-mediated PYY release modulated net ion transport across the gut mucosa. Intracerebroventricular (i.c.v.) and intraperitoneal (i.p.) administration of L-Arg suppressed food intake in rats. CONCLUSIONS L-Arg reduced food intake and stimulated gut hormone release in rodents. The anorectic effect of L-Arg is unlikely to be mediated by GLP-1 and PYY, does not require GPRC6A signalling and is not mediated via the vagus. I.c.v. and i.p. administration of L-Arg suppressed food intake in rats, suggesting that L-Arg may act on the brain to influence food intake. Further work is required to determine the mechanisms by which L-Arg suppresses food intake and its utility in the treatment of obesity.
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MESH Headings
- Animals
- Appetite Depressants/administration & dosage
- Appetite Depressants/adverse effects
- Appetite Depressants/pharmacology
- Appetite Depressants/therapeutic use
- Arginine/administration & dosage
- Arginine/adverse effects
- Arginine/therapeutic use
- Cells, Cultured
- Dietary Supplements/adverse effects
- Energy Intake/drug effects
- Energy Metabolism/drug effects
- Gastrointestinal Agents/administration & dosage
- Gastrointestinal Agents/adverse effects
- Gastrointestinal Agents/pharmacology
- Gastrointestinal Agents/therapeutic use
- Glucagon-Like Peptide 1/agonists
- Glucagon-Like Peptide 1/blood
- Glucagon-Like Peptide 1/metabolism
- In Vitro Techniques
- Injections, Intraperitoneal
- Injections, Intraventricular
- Intestinal Mucosa/cytology
- Intestinal Mucosa/drug effects
- Intestinal Mucosa/metabolism
- Intestinal Mucosa/pathology
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Obesity/diet therapy
- Obesity/drug therapy
- Obesity/metabolism
- Obesity/pathology
- Peptide YY/agonists
- Peptide YY/blood
- Peptide YY/metabolism
- Random Allocation
- Rats, Wistar
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Weight Loss/drug effects
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Affiliation(s)
- A Alamshah
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - A K McGavigan
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - E Spreckley
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - J S Kinsey-Jones
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - A Amin
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - I R Tough
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - H C O'Hara
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - A Moolla
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - K Banks
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - R France
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - G Hyberg
- AstraZeneca R&D, Mölndal, Sweden
| | - M Norton
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - W Cheong
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - A Lehmann
- AstraZeneca R&D, Mölndal, Sweden
- Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - S R Bloom
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
| | - H M Cox
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - K G Murphy
- Section of Endocrinology and Investigative Medicine, Department of Medicine, Imperial College London, London, UK
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7
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Córdoba-Chacón J, Gahete MD, Pozo-Salas AI, Castaño JP, Kineman RD, Luque RM. Endogenous somatostatin is critical in regulating the acute effects of L-arginine on growth hormone and insulin release in mice. Endocrinology 2013; 154:2393-8. [PMID: 23696563 PMCID: PMC3689276 DOI: 10.1210/en.2013-1136] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
l-arginine (l-Arg) rapidly stimulates GH and insulin release in vivo. It has been hypothesized that l-Arg stimulates GH release by lowering hypothalamic somatostatin (SST) tone. l-Arg may also act directly at the pituitary to stimulate GH release. Moreover, l-Arg has a direct stimulatory effect on β-cells, which is thought to be blunted by the release of SST from pancreatic δ-cells. To confirm the role of endogenous SST on l-Arg-induced GH and insulin release, wild-type (WT) and SST-knockout (SST-KO) mice were injected with l-Arg (ip; 0.8 g/kg), and pre-/post-injection GH, insulin, and glucose levels were measured. In WT mice, l-Arg evoked a 6-fold increase in circulating GH. However, there was only a modest increase in GH levels in WT pituitary cell cultures treated with l-Arg. In contrast, l-Arg failed to increase GH in SST-KO beyond their already elevated levels. These results further support the hypothesis that the primary mechanism by which l-Arg acutely increases GH in vivo is by lowering hypothalamic SST input to the pituitary and not via direct pituitary effects. Additionally, l-Arg induced a clear first-phase insulin secretion in WT mice, but not in SST-KO. However, SST-KO, but not WT mice, displayed a robust and sustained second-phase insulin release. These results further support a role for endogenous SST in regulating l-Arg-mediated insulin release.
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Olinto SCF, Adrião MG, Castro-Barbosa T, Goulart-Silva F, Nunes MT. Arginine induces GH gene expression by activating NOS/NO signaling in rat isolated hemi-pituitaries. Braz J Med Biol Res 2012; 45:1066-73. [PMID: 22641416 PMCID: PMC3854151 DOI: 10.1590/s0100-879x2012007500094] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 05/16/2012] [Indexed: 11/22/2022] Open
Abstract
The amino acid arginine (Arg) is a recognized secretagogue of growth hormone (GH), and has been shown to induce GH gene expression. Arg is the natural precursor of nitric oxide (NO), which is known to mediate many of the effects of Arg, such as GH secretion. Arg was also shown to increase calcium influx in pituitary cells, which might contribute to its effects on GH secretion. Although the mechanisms involved in the effects of Arg on GH secretion are well established, little is known about them regarding the control of GH gene expression. We investigated whether the NO pathway and/or calcium are involved in the effects of Arg on GH gene expression in rat isolated pituitaries. To this end, pituitaries from approximately 170 male Wistar rats (~250 g) were removed, divided into two halves, pooled (three hemi-pituitaries) and incubated or not with Arg, as well as with different pharmacological agents. Arg (71 mM), the NO donor sodium nitroprusside (SNP, 1 and 0.1 mM) and a cyclic guanosine monophosphate (cGMP) analogue (8-Br-cGMP, 1 mM) increased GH mRNA expression 60 min later. The NO acceptor hemoglobin (0.3 µM) blunted the effect of SNP, and the combined treatment with Arg and L-NAME (a NO synthase (NOS) inhibitor, 55 mM) abolished the stimulatory effect of Arg on GH gene expression. The calcium channel inhibitor nifedipine (3 µM) also abolished Arg-induced GH gene expression. The present study shows that Arg directly induces GH gene expression in hemi-pituitaries isolated from rats, excluding interference from somatostatinergic neurons, which are supposed to be inhibited by Arg. Moreover, the data demonstrate that the NOS/NO signaling pathway and calcium mediate the Arg effects on GH gene expression.
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Affiliation(s)
- S C F Olinto
- Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, Ituiutaba, MG, Brasil
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9
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de Castro Barbosa T, de Carvalho JEN, Poyares LL, Bordin S, Machado UF, Nunes MT. Potential role of growth hormone in impairment of insulin signaling in skeletal muscle, adipose tissue, and liver of rats chronically treated with arginine. Endocrinology 2009; 150:2080-6. [PMID: 19106217 DOI: 10.1210/en.2008-1487] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We have shown that rats chronically treated with Arginine (Arg), although normoglycemic, exhibit hyperinsulinemia and decreased blood glucose disappearance rate after an insulin challenge. Attempting to investigate the processes underlying these alterations, male Wistar rats were treated with Arg (35 mg/d), in drinking water, for 4 wk. Rats were then acutely stimulated with insulin, and the soleus and extensorum digitalis longus muscles, white adipose tissue (WAT), and liver were excised for total and/or phosphorylated insulin receptor (IR), IR substrate 1/2, Akt, Janus kinase 2, signal transducer and activator of transcription (STAT) 1/3/5, and p85alpha/55alpha determination. Muscles and WAT were also used for plasma membrane (PM) and microsome evaluation of glucose transporter (GLUT) 4 content. Pituitary GH mRNA, GH, and liver IGF-I mRNA expression were estimated. It was shown that Arg treatment: 1) did not affect phosphotyrosine-IR, whereas it decreased phosphotyrosine-IR substrate 1/2 and phosphoserine-Akt content in all tissues studied, indicating that insulin signaling is impaired at post-receptor level; 2) decreased PM GLUT4 content in both muscles and WAT; 3) increased the pituitary GH mRNA, GH, and liver IGF-I mRNA expression, the levels of phosphotyrosine-STAT5 in both muscles, phosphotyrosine-Janus kinase 2 in extensorum digitalis longus, phosphotyrosine-STAT3 in liver, and WAT as well as total p85alpha in soleus, indicating that GH signaling is enhanced in these tissues; and 4) increased p55alpha total content in muscles, WAT, and liver. The present findings provide the molecular mechanisms by which insulin resistance and, by extension, reduced GLUT4 content in PM of muscles and WAT take place after chronic administration of Arg, and further suggest a putative role for GH in its genesis, considering its diabetogenic effect.
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Affiliation(s)
- Thais de Castro Barbosa
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900 São Paulo, São Paulo, Brazil
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10
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de Castro Barbosa T, Lourenço Poyares L, Fabres Machado U, Nunes MT. Chronic oral administration of arginine induces GH gene expression and insulin resistance. Life Sci 2006; 79:1444-9. [PMID: 16723138 DOI: 10.1016/j.lfs.2006.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 03/16/2006] [Accepted: 04/15/2006] [Indexed: 11/29/2022]
Abstract
Arginine (Arg) presents a potent growth hormone (GH) releasing activity. In vivo and in vitro studies carried out in our laboratory have demonstrated that acute treatment with Arg also increases GH gene expression. Taking into account the recognizable diabetogenic role of GH and that Arg increases insulin release, this study aimed at evaluating the effects of oral chronic administration of Arg on GH gene expression, by Northern blotting analysis, and on the insulin sensitivity, by means of the Insulin Tolerance Test (ITT), blood glucose decay rate (kitt) and insulin plasma concentration. We demonstrated that rats that consumed Arg ( approximately 35 mg/day) in drinking water, during 4 weeks, presented an increase in GH mRNA content (p < 0.01), a decreased peripheral response to insulin, as shown by the reduced blood glucose decay rate (p < 0.05), and a higher insulin plasma concentration (p < 0.01) than control group. Arg treatment did not modify the animals' food and water intake, while it decreased the heart rate and the arterial blood pressure compared to control group (p < 0.05). According to the results presented herein we conclude that chronic oral administration of arginine increases GH gene expression and induces insulin resistance. The arterial blood pressure decrease has already been pointed out in the literature, and seems to occur in response to the dilating effect of nitric oxide generated from Arg, as well as from NO generation in central and peripheral neuronal populations that express NOS and are involved in the autonomic regulation of the cardiac function.
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Affiliation(s)
- Thais de Castro Barbosa
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-900, São Paulo, SP, Brazil
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11
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Jain-Vakkalagadda B, Pal D, Gunda S, Nashed Y, Ganapathy V, Mitra AK. Identification of a Na+-dependent cationic and neutral amino acid transporter, B(0,+), in human and rabbit cornea. Mol Pharm 2005; 1:338-46. [PMID: 16026003 DOI: 10.1021/mp0499499] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to identify and functionally characterize an active transport system for L-arginine on rabbit corneal epithelium and human cornea and study its interaction with the amino acid ester prodrugs of acyclovir (Anand, B. S.; Mitra, A. K. Pharm. Res. 2002, 19, 1194-1202). Transport characteristics of [3H]-L-arginine across freshly excised rabbit corneas were determined at various concentrations, in the absence of sodium and chloride ions. Inhibition studies were conducted in the presence of other amino acids, ouabain, and amino acid ester prodrugs of acyclovir (glycine-ACV, phenylalanine-ACV and gamma-glutamate-ACV). Reverse transcription-polymerase chain reaction (RT-PCR) for amino acid transporter B(0,+) was carried out on total RNA isolated from rabbit cornea, rabbit corneal epithelium, and human cornea. Transport of L-Arg across rabbit cornea was saturable (Km = 306 +/- 72 microM and Vmax = 0.12 +/- 0.01 nmol min(-1) cm(-2)) and was Na+, Cl-, and energy dependent. Transport was inhibited by neutral and cationic amino acids and a B(0,+) system specific inhibitor, BCH (Sloan, J. L.; Mager, S. J. Biol. Chem. 1999, 274, 23740-23745), but not by anionic amino acids. Amino acid prodrugs of ACV (Glu-ACV and Phe-ACV) also inhibited transport of [3H]-L-Arg across rabbit cornea. Amino acid transporter B(0,+) was identified by RT-PCR and its identity confirmed by subcloning and sequencing in rabbit cornea, rabbit corneal epithelium, and human cornea. A Na+-, Cl(-)-, and energy-dependent carrier for L-Arg, B(0,+), was identified on rabbit corneal epithelium and human cornea. Glu-ACV and Phe-ACV appear to be substrates for this transporter. The presence of such transporters on the corneal epithelium may provide new opportunities for transporter-targeted prodrug design for enhanced corneal absorption.
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Affiliation(s)
- Blisse Jain-Vakkalagadda
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5005 Rockhill Road, Kansas City, Missouri 64110-2499, USA
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12
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Trueta C, Méndez B, De-Miguel FF. Somatic exocytosis of serotonin mediated by L-type calcium channels in cultured leech neurones. J Physiol 2003; 547:405-16. [PMID: 12562971 PMCID: PMC2342656 DOI: 10.1113/jphysiol.2002.030684] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We studied somatic exocytosis of serotonin and its mediation by L-type calcium (Ca2+) channels in cultured Retzius neurones of the leech. Exocytosis was induced by trains of impulses at different frequencies or by depolarisation with 40 mM potassium (K+), and was quantified by use of the fluorescent dye FM 1-43. Stimulation increased the membrane fluorescence and produced a pattern of FM 1-43 fluorescent spots of 1.28 +/- 0.01 microm in diameter, provided that Ca2+ was present in the bathing fluid. Individual spots lost their stain during depolarisation with 40 mM K+. Electron micrographs showed clusters of dense core vesicles, some of which were in contact with the cell membrane. Presynaptic structures with clear vesicles were absent from the soma. The number of fluorescent spots per soma, but not their diameter or their fluorescence intensity, depended on the frequency of stimulation. Trains at 1 Hz produced 19.5 +/- 5 spots per soma, 77.9 +/- 13.9 spots per soma were produced at 10 Hz and 91.5 +/- 16.9 spots per soma at 20 Hz. Staining patterns were similar for neurones in culture and in situ. In the presence of the L-type Ca2+ channel blocker nimodipine (10 microM), a 20 Hz train produced only 22.9 +/- 6.4 spots per soma, representing a 75 % reduction compared to control cells (P < 0.05). Subsequent incubation with 10 mM caffeine to induce Ca2+ release from intracellular stores increased the number of spots to 73.22 +/- 12.5. Blockers of N-, P-, Q- or invertebrate Ca2+ channels did not affect somatic exocytosis. Our results suggest that somatic exocytosis by neurones shares common mechanisms with excitable endocrine cells.
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Affiliation(s)
- Citlali Trueta
- Departamento de Biofísica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, D.F., México
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13
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Sloan JL, Grubb BR, Mager S. Expression of the amino acid transporter ATB 0+ in lung: possible role in luminal protein removal. Am J Physiol Lung Cell Mol Physiol 2003; 284:L39-49. [PMID: 12388375 DOI: 10.1152/ajplung.00164.2002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Normal lung function requires transepithelial clearance of luminal proteins; however, little is known about the molecular mechanisms of protein transport. Protein degradation followed by transport of peptides and amino acids may play an important role in this process. We previously cloned and functionally characterized the neutral and cationic amino acid transporter ATB(0+) and showed expression in the lung by mRNA analysis. In this study, the tissue distribution, subcellular localization, and function of the transporter in native tissue were investigated. Western blots showed expression of the ATB(0+) protein in mouse lung, stomach, colon, testis, blastocysts, and human lung. Immunohistochemistry revealed that ATB(0+) is predominantly expressed on the apical membrane of ciliated epithelial cells throughout mouse airways from trachea to bronchioles and in alveolar type I cells. Electrical measurements from mouse trachea preparations showed Na(+)- and Cl(-)-dependent, amino acid-induced short-circuit current consistent with the properties of ATB(0+). We hypothesize that, by removing amino acids from the airway lumen, the transporter contributes to protein clearance and, by maintaining a low nutrient environment, plays a role in lung defense.
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Affiliation(s)
- Jennifer L Sloan
- Department of Cell and Molecular Physiology and the Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, NC 27599, USA
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14
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Tunnicliff G. Membrane glycine transport proteins. J Biomed Sci 2003; 10:30-6. [PMID: 12566983 DOI: 10.1007/bf02255994] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2002] [Accepted: 09/01/2002] [Indexed: 11/24/2022] Open
Abstract
Structurally, the simplest amino acid is glycine, and it has a number of important yet distinct functions in the body. This review focuses on the different transport systems and the associated carrier proteins for glycine that are responsible for its movement across biological membranes. Transport proteins in the class GLYT appear to be the most specific for glycine. However, the B0+ system also carries significant amounts of glycine. Other amino acid transport systems capable of carrying small amounts of glycine are ASC, asc and system L. In addition, an ATP-dependent transport process exists that takes up glycine into synaptic vesicles at nerve endings. This is known as the vesicular inhibitory amino acid transporter since, in addition to glycine, it can transport possibly two other inhibitory neurotransmitters.
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Affiliation(s)
- Godfrey Tunnicliff
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Evansville, Ind. 47712, USA.
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15
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Nass R, Pezzoli SS, Chapman IM, Patrie J, Hintz RL, Hartman ML, Thorner MO. IGF-I does not affect the net increase in GH release in response to arginine. Am J Physiol Endocrinol Metab 2002; 283:E702-10. [PMID: 12217887 DOI: 10.1152/ajpendo.00075.2002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Arginine stimulates growth hormone (GH) secretion, possibly by inhibiting hypothalamic somatostatin (SS) release. Insulin-like growth factor I (IGF-I) inhibits GH secretion via effects at the pituitary and/or hypothalamus. We hypothesized that if the dominant action of IGF-I is to suppress GH release at the level of the pituitary, then the arginine-induced net increase in GH concentration would be unaffected by an IGF-I infusion. Eight healthy young adults (3 women, 5 men) were studied on day 2 of a 47-h fast for 12 h (35th-47th h) on four occasions. Saline (Sal) or 10 microg. kg(-1). h(-1) recombinant human IGF-I was infused intravenously for 5 h from 37 to 42 h of the 47-h fast. Arginine (Arg) (30 g iv) or Sal was infused over 30 min during the IGF-I or Sal infusion from 40 to 40.5 h of the fast. Subjects received the following combinations of treatments in random order: 1) Sal + Sal; 2) Sal + Arg; 3) IGF-I + Sal; 4) IGF-I + Arg. Peak GH concentration on the IGF-I + Arg day was ~45% of that on the Sal + Arg day. The effect of arginine on net GH release was calculated as [(Sal + Arg) - (Sal + Sal)] - [(IGF-I + Arg) - (IGF-I + Sal)]. There was no significant effect of IGF-I on net arginine-induced GH release over control conditions. These findings suggest that the negative feedback effect of IGF-I on GH secretion is primarily mediated at the pituitary level and/or at the hypothalamus through a mechanism different from the stimulatory effect of arginine.
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Affiliation(s)
- Ralf Nass
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia, Charlottesville, Virginia 22908, USA
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Fonteriz RI, Villalobos C, García-Sancho J. An extracellular sulfhydryl group modulates background Na(+) conductance and cytosolic Ca(2+) in pituitary cells. Am J Physiol Cell Physiol 2002; 282:C864-72. [PMID: 11880275 DOI: 10.1152/ajpcell.00441.2001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Treatment of GH(3) pituitary cells with p-chloromercurybenzenesulfonate (PCMBS) increased the cytosolic Ca(2+) concentration ([Ca(2+)](i)). This effect was reversed by dithiothreitol and blocked by L-type Ca(2+) channel antagonists or Na(+) removal. PCMBS increased membrane conductance and depolarized the plasma membrane. Apart from minor effects on K(+) and Ca(2+) channels, PCMBS increased (6 times at -80 mV) an inward Na(+) current whose properties were similar to those of a background Na(+) conductance (BNC) described previously, necessary for generation of spontaneous electrical activity. In rat lactotropes and somatotropes in primary culture, PCMBS also produced a Na(+)-dependent [Ca(2+)](i) increase, whereas little or no effect was observed in thyrotropes, corticotropes, and gonadotropes. The Na(+) conductance elicited by PCMBS in somatotropes seemed to be the same as that stimulated by the hypothalamic growth hormone (GH)-releasing hormone, which regulates membrane excitability and GH secretion. The BNC studied here could play a physiological role, regulating excitability and spontaneous activity, and explains satisfactorily the [Ca(2+)](i)-increasing actions of the mercurials reported previously in several excitable tissues.
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Affiliation(s)
- Rosalba I Fonteriz
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior Investigaciones Científicas, Departamento de Fisiología y Bioquímica, Facultad de Medicina, 47005 Valladolid, Spain
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17
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Fisher TE, Bourque CW. The function of Ca(2+) channel subtypes in exocytotic secretion: new perspectives from synaptic and non-synaptic release. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2001; 77:269-303. [PMID: 11796142 DOI: 10.1016/s0079-6107(01)00017-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
By mediating the Ca(2+) influx that triggers exocytotic fusion, Ca(2+) channels play a central role in a wide range of secretory processes. Ca(2+) channels consist of a complex of protein subunits, including an alpha(1) subunit that constitutes the voltage-dependent Ca(2+)-selective membrane pore, and a group of auxiliary subunits, including beta, gamma, and alpha(2)-delta subunits, which modulate channel properties such as inactivation and channel targeting. Subtypes of Ca(2+) channels are constituted by different combinations of alpha(1) subunits (of which 10 have been identified) and auxiliary subunits, particularly beta (of which 4 have been identified). Activity-secretion coupling is determined not only by the biophysical properties of the channels involved, but also by the relationship between channels and the exocytotic apparatus, which may differ between fast and slow types of secretion. Colocalization of Ca(2+) channels at sites of fast release may depend on biochemical interactions between channels and exocytotic proteins. The aim of this article is to review recent work on Ca(2+) channel structure and function in exocytotic secretion. We discuss Ca(2+) channel involvement in selected types of secretion, including central neurotransmission, endocrine and neuroendocrine secretion, and transmission at graded potential synapses. Several different Ca(2+) channel subtypes are involved in these types of secretion, and their function is likely to involve a variety of relationships with the exocytotic apparatus. Elucidating the relationship between Ca(2+) channel structure and function is central to our understanding of the fundamental process of exocytotic secretion.
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Affiliation(s)
- T E Fisher
- Department of Physiology, University of Saskatchewan, 107 Wiggins Road, Sask., S7N 5E5, Saskatoon, Canada.
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18
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Sloan JL, Mager S. Cloning and functional expression of a human Na(+) and Cl(-)-dependent neutral and cationic amino acid transporter B(0+). J Biol Chem 1999; 274:23740-5. [PMID: 10446133 DOI: 10.1074/jbc.274.34.23740] [Citation(s) in RCA: 243] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A Na(+)-dependent neutral and cationic amino acid transport system (B(0+)) plays an important role in many cells and tissues; however, the molecular basis for this transport system is still unknown. To identify new transporters, the expressed sequence tag database was queried, and cDNA fragments with sequence similarity to the Na(+)/Cl(-)-dependent neurotransmitter transporter family were identified. Based on these sequences, rapid amplification of cDNA ends of human mammary gland cDNA was used to obtain a cDNA of 4.5 kilobases (kb). The open reading frame encodes a 642-amino acid protein named amino acid transporter B(0+). Human ATB(0+) (hATB(0+)) is a novel member of the Na(+)/Cl(-)-dependent neurotransmitter transporter family with the highest sequence similarity to the glycine and proline transporters. Northern blot analysis identified transcripts of approximately 4.5 kb and approximately 2 kb in the lung. Another tissue survey suggests expression in the trachea, salivary gland, mammary gland, stomach, and pituitary gland. Electrophysiology and radiolabeled amino acid uptake measurements were used to functionally characterize the transporter expressed in Xenopus oocytes. hATB(0+) was found to transport both neutral and cationic amino acids, with the highest affinity for hydrophobic amino acids and the lowest affinity for proline. Amino acid transport was Na(+) and Cl(-)-dependent and was attenuated in the presence of 2-aminobicyclo-[2.2.1]-heptane-2-carboxylic acid, a system B(0+) inhibitor. These characteristics are consistent with system B(0+) amino acid transport. Thus, hATB(0+) is the first cloned B(0+) amino acid transporter.
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Affiliation(s)
- J L Sloan
- Department of Cell and Molecular Physiology and the Curriculum in Neurobiology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Affiliation(s)
- S Chappel
- Serono Laboratories, Norwell, Massachusetts, USA
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